a) Field of the Invention
The invention is directed to a method for the production of window elements which can be soldered into a housing in a hermetically tight manner and of a window element sealing a housing. Window elements of this kind are particularly suitable for closing housings of radiation detectors in a vacuum-tight manner while ensuring optical functions.
b) Description of the Related Art
Constructions of window elements which are soldered into housings of radiation detectors for the purpose of a gas-tight or vacuum-tight connection are known especially for infrared detectors, e.g., from JP 11-211555.
Generally, the windows can be optically coated in a mask. Next, a metal coating is applied to the masked areas on the surface and to the lateral edge of the window. The solder connection is later implemented by way of this metal coating. The metal coating can be applied chemically (JP 01-039528) or by sputtering (DE 102 40 355 A1).
A problem arising in this connection is the insufficient quality of the transitional area between the optical coating and metal coating. For example, residues of optical coating materials can lead to problems with adherence in the region of the metal coating which impair a tight soldering connection of the window to the detector housing. Further, application of the metal coating can interfere with the properties of the optical layers, e.g., due to adherence problems or entry of scattered light or unwanted light at defective locations.